1. Technical Field
The present invention relates to refractive optical systems and, more particularly, to a compact refractive optical system which provides an extremely wide field of view.
2. Discussion
In certain imaging applications, an extremely wide field of view optical system is required so that a very large two dimensional region of the object space may be covered and searched in a short period of time. Due to the large amount of spatial information to be collected while covering this large field of view, and due to the state of the art in detector array technology, particularly in the infrared portion of the spectrum, it is desirable in such imaging applications to utilize linear detector array technology. The use of a linear detector array dictates the need for some type of scanning technique and device, which allows the linear array to cover a two dimensional field of view. Further, it is desirable that this scanning technique and device be such that the detector assembly which includes the detector array, electronics and cryogenics, to be located on a stationary portion of the optical system. This latter desire is motivated by the difficulties associated with transferring electrical power and signals and cryogenic connections across a dynamic interface.
It is desirable to provide a refractive optical system, which provides search and acquisition capability, that would be useful in a variety of applications. Such applications are full earth surveillance from low altitude space platforms, missile launch warning from an airborne platform, or airborne threat detection from a ground base location.
Prior optical systems which attempt to provide such capabilities typically do not provide the required field of view, are much too large in size and weight, or employ a highly complex and power intensive scanning technique, or often fail to locate the detector array, cryogenics, and electronics off the scanning part of the sensor. Further attempts to fulfil the above applications often make use of optic technology which has not been demonstrated, such as a low loss flexible multi-element fiber optic reformatter.
Thus, there exists a need in the field to provide an optical system which provides a requisite wide field of view, is relatively compact in both size and weight, eliminates complex and power intensive scanning techniques, and which locates the detector array, cryogenics, and electronics off of the scanning part of the sensor.